JP7379859B2 - Light sources, projection devices, measurement devices, robots, electronic devices, moving objects, and modeling devices - Google Patents

Description

The present invention relates to a light source, a projection device, a measuring device, a robot, an electronic device, a moving object, and a modeling device.

Laser light sources have advantages that LEDs (Light Emitting Diodes) do not have, such as high output through resonator amplification and focus-free properties, and are used in various devices such as projectors and distance measurement. However, coherence, which is a characteristic property of laser light, causes a speckled pattern called speckle noise to occur on the retina of the eye and the image sensor of a camera, which are the viewing surfaces for observing the irradiated target. Speckle noise has a negative effect on image quality and measurement accuracy, which is a disadvantage when using a laser, so it is necessary to reduce speckle noise when using a laser.

For the purpose of reducing speckle noise, a laser light source has been disclosed that has a surface-emitting semiconductor laser array having a plurality of light-emitting sections and a control section that controls the plurality of light-emitting sections and switches the light emission pattern (Patent No. (See Reference 1).

However, conventional methods for reducing speckle noise involve changing the speckle pattern by modifying the light source or the light receiving side, and then reducing noise by averaging (superimposing) them. However, there is a problem in that the cost increases due to the enlargement of the light projector and the complexity of the system.

The present invention has been made in view of the above, and provides a light source, a projection device, a measuring device, a robot, and an electronic device that can reduce speckle noise without increasing the size or cost of the light projecting unit. , a moving object, and a modeling device.

In order to solve the above-mentioned problems and achieve the objects, a light source according to an embodiment of the present invention has a plurality of light emitting elements each emitting light of a predetermined oscillation wavelength in a plane, and the plurality of light emitting elements The element arrangement of the elements is such that in the assumed projection area, the irradiated light of the plurality of light emitting elements satisfies the element spacing that overlaps, and the speckle pattern of each of the irradiated lights obtained in the assumed projection area is different for each irradiated light. A light emitting element group that satisfies the interval and includes at least one light emitting element having a different oscillation wavelength is set as the minimum unit of the plurality of light emitting elements, and a plurality of light emitting element groups of the plurality of minimum units are set as the light emitting elements having the same oscillation wavelength. are arranged so as to take periodic positions, and the light emitting elements included in the minimum unit light emitting element group have a wavelength difference between the oscillation wavelength of the light emitted by the adjacent light emitting element and the light emission wavelength of the minimum unit. It is characterized in that the oscillation wavelength of light emitted by the light emitting elements included in the element group is larger than the wavelength difference when they are arranged in order of wavelength.

According to the present invention, it is possible to reduce speckle noise without increasing the size or cost of the light projecting section.

FIG. 1 is a conceptual diagram showing the principle of generation of laser speckle noise. FIG. 2 is a diagram showing the relationship between the interval between light sources and the angle of incidence on an observation point. FIG. 3 is a diagram showing experimental results when a 40 cH-VCSEL light source (λ=780 nm) with a pitch between light emitting elements of 50 μm or less is used. FIG. 4 is a diagram showing an example of experimental results when changing θ. FIG. 5 is a diagram showing an example of the layout configuration of the VCSEL array according to the first embodiment. FIG. 6 is a diagram showing an example of a speckle photographed image when 1 cH (one light emitting element) is lit using the VCSEL array shown in FIG. 5, and when all 100 cH are lit. FIG. 7 is a diagram showing experimental results of the speckle noise reduction effect when using the VCSEL array according to Example 1. FIG. 8 is a diagram showing an example of a layout configuration of a VCSEL array according to the second embodiment. FIG. 9 is a diagram illustrating an example in which the order of the light emitting elements of different wavelengths in the set is randomized. FIG. 10 is a diagram showing a modified example of the configuration of the VCSEL array. FIG. 11 is a diagram showing an example of the configuration of a projection device according to the second embodiment. FIG. 12 is a diagram illustrating an example of the configuration of the optical deflection element. FIG. 13 is a diagram showing an example of a measuring device according to the third embodiment. FIG. 14 is a diagram showing an example of the block configuration of the measuring device. FIG. 15 is a diagram showing an example of the configuration of a robot according to the fourth embodiment. FIG. 16 is a diagram illustrating an example of the configuration of an electronic device such as a smartphone according to the fourth embodiment. FIG. 17 is a diagram showing an example of the configuration of a vehicle according to the fifth embodiment. FIG. 18 is a diagram illustrating an example of the configuration of another moving body according to the fifth embodiment. FIG. 19 is a diagram showing an example of the configuration of a 3D printer according to the sixth embodiment.

Embodiments of a light source, a projection device, a measuring device, a robot, an electronic device, a moving object, and a modeling device will be described below with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments.

(First embodiment)
First, the speckles appearing on the observation surface and the principle of eliminating the speckles according to the first embodiment will be explained.

FIG. 1 is a conceptual diagram showing the principle of generation of laser speckles (speckle noise). FIG. 1A shows a system including a laser light source 1000, a screen 1001, and a camera 1002. FIG. 1B shows an observed image (speckle image) 1003 observed by the camera 1002 when a solid image is projected from the laser light source 1000 onto the screen 1001. This observation image 1003 includes speckles developed on the image sensor of the camera 1002.

When a solid image is projected onto the screen 1001 from the laser light source 1000, a portion of the light P1 constituting the solid image is multiple-scattered inside the surface of the screen 1001. This multiple scattered light comes out from inside the surface of the screen 1001, but the scattered light P2 that comes out has a random phase component added to it due to the shape of the irregularities (unevenness) on the surface of the screen 1001. There is. The scattered light P2 is converged on the observation surface (imaging device) of the camera 1002 via an optical system such as a lens, and since the laser light is coherent light, the scattered light P2 interferes with each other and overlaps on the observation surface. As a result, bright and dark areas appear randomly on the observation surface, and a spotted speckle pattern is observed. This flickering of brightness and darkness is a source of noise that adversely affects image quality and various measurements. This phenomenon is a complex phenomenon that involves all the elements of the light emitting system, the object, and the light receiving system, and the observed speckle pattern changes greatly depending on the lens of the camera 1002, the pixel size of the image sensor, and the like.

Although FIG. 1B shows an observed image 1003 when observed with the camera 1002, it is also possible to observe the solid image projected on the screen 1001 not with the camera 1002 but with a laser display or other human eyes. A similar speckle pattern appears on the retina.

Next, it will be qualitatively explained that speckle noise can be reduced. First, the index of speckle noise will be explained. The following equation (1) is an equation representing speckle contrast (Cs) used as an index of speckle noise.
Cs=σ/S...(1)

In equation (1), S is the average brightness value of the captured image when a solid image is projected, and σ is the standard deviation. As shown in equation (1), Cs is expressed as the reciprocal of the signal-to-noise ratio (SNR), which indicates general signal strength. The lower the contrast value shown by Cs in Equation (1), the lower the speckle noise and the less flickering the image has.

The speckle pattern observed on the observation surface is complex, involving all elements of the light emitting system, object, and light receiving system. Generally, if there are a plurality of laser light sources 1000, the speckle patterns developed by each laser light source 1000 are not the same but random. Therefore, if a plurality of laser light sources 1000 are provided, different speckle patterns are generated for each laser light source 1000, and these speckle patterns are superimposed on the observation surface, the plurality of random speckle patterns will cause speckle noise on the observation surface. are averaged, and speckle noise is reduced.

Based on this idea, formula (1) is further modified regarding the relationship between averaging and reduction of speckle noise. For n speckle patterns (where n is a natural number) that overlap on the observation surface (the image of each speckle pattern is called a speckle image), the average brightness of the speckle image k is S _k , the standard deviation is σ _k , Let the speckle contrast be Cs _k . In this case, if the laser light source 1000 as the irradiation source has the same power, the average brightness S _k , standard deviation σ _k , and speckle contrast Cs _k of each speckle image will be equal, so the following equations (2) to (4) ) can be considered to be the relationship.
_S1 = _S2 = _S3 =...= _Sn =S...(2)
σ ₁ = σ ₂ = σ ₃ =...=σ _n =σ (3)
Cs ₁ =Cs ₂ =Cs ₃ =...=Cs _n =Cs...(4)

Therefore, the brightness value S _SUM when n speckle images are combined becomes the following equation (5) by applying the condition of equation (2).
S _SUM =S ₁ +S ₂ +S ₃ +...+S _n =S×n...(5)

Further, regarding the standard deviation σ _SUM , the additivity of the variance in the following equation (6) can be used.
σ _SUM ² = σ ₁ ² +σ ₂ ² +σ ₃ ² +...+σ _n ² ...(6)

By applying the condition of equation (3) to equation (6), the following equation (7) is obtained.
σ _SUM =√(σ ² ×n)=σ√n...(7)

From the above, the speckle contrast (Cs _SUM ) of an observed image observed by superimposing n speckle images is expressed by the following equation (8).

Cs _SUM =σ√n/(S×n)=(√n/n)×(σ/S)=1/√n×Cs
...(8)
Equation (8) indicates that the speckle contrast is improved (reduced) to 1/√n by averaging n speckle images. Therefore, in the calculation, it can be expected that the speckle contrast (Cs) is improved by 1/√n when the number of laser light sources 1000 is n.

Here, in order to obtain the above calculation result, it is necessary to superimpose a plurality of random speckle patterns, that is, it is assumed that the speckle patterns that appear depending on each laser light source 1000 are different. This problem can be achieved, for example, by using multiple source angle multiplexing. Multiple light source angle multiplexing multiplexes speckle images using a method that generates different speckle patterns for each light source by varying the angle of incidence of light on the observation point for each light source. Therefore, below, as an example, angle multiplexing of a plurality of light sources will be used, and the setting of a surface-emitting semiconductor laser that satisfies the above equation (8) will be discussed.

FIG. 2 is a diagram showing the relationship between the interval between light sources and the angle of incidence on an observation point. The system shown in FIG. 2 includes a camera 1002, a screen 1001, and a VCSEL (Vertical Cavity Surface Emitting LASER) light source 1100.

The VCSEL light source 1100 is an example of a "surface-emitting semiconductor laser." The VCSEL light source 1100 has a large number of light emitting elements 1101 corresponding to the laser light source 1000 in a plane. Here, only two light emitting elements 1101 out of a large number of light emitting elements 1101 are shown for explanation of the incident angle. Each light emitting element 1101 is an element such as a semiconductor laser diode that emits coherent light.

A white diffuser plate is used for the screen 1001. In this system, by changing the distance (LWD) from the VCSEL light source 1100 to the screen 1001 and the distance (D) between the two light emitting elements 1101 of the VCSEL light source 1100, each of the lights incident on the screen 1001 from the two light emitting elements 1101 can be changed. The angle θ formed by the light changes. For example, increasing the distance (D) between the light emitting elements 1101 increases θ, and increasing the distance (LWD) to the screen 1001 decreases θ. In other words, the value of θ can be changed by adjusting the interval between the light sources.

FIG. 3 is a diagram showing experimental results when a 40 cH-VCSEL light source with a pitch (D) between light emitting elements of 50 μm or less is used. The oscillation wavelength of each light emitting element is uniformly λ=780 nm. In FIG. 3, the measurement results of speckle noise are plotted, with the horizontal axis representing the number of lighting light sources (n) and the vertical axis representing the rate of change in speckle contrast (Cs). Note that the vertical axis represents the rate of change when the speckle pattern when n=1 is used as the standard for speckle contrast (Cs).

The broken line graph in FIG. 3 is a curve (theoretical value curve) representing the theoretical value of 1/√n shown by equation (8). From this measurement result, it can be seen that the speckle contrast (Cs) decreases following the theoretical value curve graph until the number of lighting light sources reaches 4 (that is, n = 4), and the speckle noise is reduced. . However, after the number of lighting light sources is n=4, even if the number of lighting light sources is increased sequentially from 4, the speckle contrast (Cs) hardly changes, and the speckle noise does not decrease as per the theoretical value.

However, even if the number of lit light sources is increased to 40, the speckle contrast (Cs) remains almost unchanged compared to when the number of lit light sources is 4, and the actual reduction effect remains at less than 1/3 of the theoretical value. .

From this result, it can be seen that simply increasing the number of lighting light sources does not reduce the speckle noise to a certain extent, and that even if the number of lighting light sources is increased, sufficient reduction of speckle noise cannot be expected. Therefore, it can be seen that simply using a plurality of light emitting elements arranged as the VCSEL light source 1100 has a limited effect of reducing speckle noise.

Therefore, the present inventor studied a design for efficiently integrating light emitting elements that contribute to speckle reduction into the VCSEL light source 1100.

In the experiment, θ was varied by gradually changing the element spacing (D) of the VCSEL light source 1100 shown in FIG. Then, for each value of θ, one light emitting element and the light emitting elements at the element interval corresponding to θ are turned on, and the screen 1001 is photographed by the camera 1002. Then, the speckle contrast (Cs) of the overlapping speckle patterns is measured for each value of θ from the image taken by the camera 1002.

FIG. 4 is a diagram showing an example of experimental results when changing θ. FIG. 4 shows experimental results where the horizontal axis is θ and the vertical axis is the rate of change in speckle contrast (Cs).

From the results shown in Figure 4, the speckle contrast (Cs) decreases as θ increases, and when it reaches approximately 0.04 to 0.05°, the theoretical value 1/√2 shown by equation (8) It can be seen that it converges to . From this experimental result, it can be seen that there is a value of θ that converges to the theoretical value of 1/√2. In the following, settings that converge to the theoretical values indicated by the experimental results will be collectively referred to as "settings that are effective in reducing speckle noise."

In this way, the value of 0.04 to 0.05° itself is not an absolute value because it changes depending on various conditions such as the geometric conditions of the camera 1002 and screen 1001 and the surface roughness of the measurement target, but the experimental results are When obtaining the effect of reducing speckle noise by multiplexing multiple light source angles using the VCSEL light source 1100, a design layout (element This suggests that some configuration may be necessary. In other words, if light emitting elements are integrated on the VCSEL light source surface at appropriate element intervals based on the experimental results, it is possible to reduce speckle noise without increasing the size or cost of the light projecting section.

Next, an example of a layout configuration of a VCSEL light source in which light emitting elements are integrated in the "setting that has the effect of reducing speckle noise" shown in the experimental results of FIG. 4 will be shown.

(Example 1)
FIG. 5 is a diagram showing an example of the layout configuration of the VCSEL array according to the first embodiment. The VCSEL array 11 shown in FIG. 5 has a layout configuration in which 100 surface-emitting light emitting elements a are arranged at equal pitches with the same element spacing within the VCSEL array surface.

In FIG. 5, the number shown at the X position of light emitting element a(X, Y) represents the row number, and the number shown at the Y position represents the column number. That is, the total number of light emitting elements a is 5 rows×20 columns=100. Note that since there is a restriction on the number of terminals, each light emitting element a is not individually turned on, but is controlled to turn on in two rows, for example 1, 2, 9, . . . , 100 and n. However, the reason for using two stripes of n each is to facilitate comparison with the theoretical value of the speckle reduction effect, and the present invention is not limited to this.

The element spacing (pitch) of each sending element a was set to 300 μm, which satisfies the following two conditions, in order to achieve a “setting that is effective in reducing speckle noise”. Note that 300 μm is shown as an example, and is not limited to this.

Condition 1: Element spacing so that the irradiated light from multiple light emitting elements overlaps in the assumed projection area

Condition 1 is such that the light from the light emitting elements at both ends of the VCSEL array 11 sufficiently overlaps in the irradiation area (projection area) of the screen, taking into account, for example, the assumed screen distance (LWD) and the radiation angle (FFP) of the light emitting elements. That is the condition. If the light from the light-emitting elements at both ends overlaps sufficiently, the light from the light-emitting elements between them should also overlap sufficiently. Note that this is an example of a case where all the arranged light sources are utilized, and a speckle reduction effect can be obtained if the element spacing is such that at least the irradiation light of adjacent light emitting elements overlaps among the plurality of light emitting elements.

Condition 2: The element spacing is such that the speckle pattern of each irradiation light obtained in the assumed projection area is different for each irradiation light.

Condition 2 is a condition indicating that, for example, at an assumed screen distance (LWD), the angle (θ) formed by each laser beam necessary for light source multiplexing can be secured to a value that converges to the theoretical value. The fact that the angle (θ) has been secured to a value that converges to the theoretical value means that the condition that the speckle pattern of each irradiation light is different for each irradiation light is satisfied even if the number of lit lights increases. .

FIG. 6 is a diagram showing an example of a speckle photographed image when 1 cH (one light emitting element) is lit using the VCSEL array 11 shown in FIG. 5, and when all 100 cH are lit. FIG. 6(a) is a speckle photographed image when 1 cH is turned on, and FIG. 6(b) is a speckle photographed image when all 100 cH are turned on.

Comparing these images, we can see that the flicker between light and dark in the image taken when 100 cH was turned on was dramatically reduced compared to the image taken when 1 cH was turned on, indicating that the speckle noise reduction effect of light source multiplexing was effective. I can see that

FIG. 7 is a diagram showing experimental results of the speckle noise reduction effect when using the VCSEL array 11 according to Example 1. Fig. 7 shows that, unlike the experimental results of the 40cH-VCSEL light source shown in Fig. 3, the speckle contrast (Cs) continues to decrease even when the number of lit light sources is increased and follows the broken line curve graph (theoretical value). A speckle noise reduction effect close to the theoretical value can be obtained.

Note that in Figure 7, there is a slight difference between the measured value plotted and the theoretical value shown by the broken line, but this difference is due to the fact that the captured image includes all fluctuation factors such as the pixel variation of the camera itself. This is thought to be a contributing factor. Furthermore, as the number of lighting light sources increases, there is a possibility that similar speckle patterns exist among them, and this is also considered to be a factor. In order to accurately measure slight differences, it is necessary to devise ways to measure minute speckle noise due to the measurement limits of the observation system itself.

From the above results, if the element spacing of the light emitting elements is appropriately set to satisfy the conditions 1 and 2 above, even when a large number of light emitting elements are provided in one VCSEL light source chip, the number of light emitting elements will be adjusted. We were able to demonstrate the effectiveness of this method in that a speckle noise reduction effect of the theoretical value of 1/√n can be obtained. Therefore, if the light emitting elements are integrated within the plane of the VCSEL light source so as to satisfy Conditions 1 and 2 above, it is possible to reduce speckle noise without increasing the size or cost of the light projecting section. become.

Note that the layout shown in FIG. 5 is an example, and the number of light emitting elements, the shape of the opening, the arrangement of the light emitting elements, etc. are not limited thereto. As long as Conditions 1 and 2 are satisfied, the number of light emitting elements, the shape of the opening, the arrangement of the light emitting elements, etc. may be modified as appropriate.

(Example 2)
FIG. 8 is a diagram showing an example of a layout configuration of a VCSEL array having light emitting elements a of different oscillation wavelengths (hereinafter referred to as wavelengths) according to the second embodiment. It shows a one-dimensional arrangement of light emitting elements a of different wavelengths (in order of wavelength, wavelength λ1, wavelength λ2, wavelength λ3, wavelength λ4, wavelength λ5).

A speckle pattern is formed when the phase-disturbed scattered light generated when a laser is irradiated onto a screen interferes with each other on the viewing surface. The phase shift of this scattered light is mainly determined by the optical path length due to the undulations (unevenness) of the screen surface and the oscillation wavelength of the laser. In the angle multiplexing of multiple light sources in Example 1, the speckle pattern is changed by changing the optical path length and changing the phase of the scattered light depending on the angle θ formed by the laser beam of each light source. On the other hand, in this second embodiment, the phase of the scattered light is changed by modulating the oscillation wavelength of the laser itself, and noise is reduced by superimposing the changed speckle pattern (wavelength multiplexing). Therefore, when wavelength multiplexing is used to obtain different speckle patterns, it is not necessarily necessary to satisfy Condition 2 for a single wavelength, and there is an advantage that layout constraints are relaxed.

In FIG. 8, one set is a light emitting element a (light emitting element group) with five different wavelengths (wavelength λ1, wavelength λ2, wavelength λ3, wavelength λ4, wavelength λ5), and a total of 10 sets (5 types This shows a layout in which light-emitting elements a (wavelength x 10 sets = 50 pieces) are arranged one-dimensionally at a pitch of 30 μm.

Within each set, the light emitting elements a are arranged in the order of predetermined wavelengths. That is, the light emitting elements a of each wavelength are arranged periodically, and the pitch of the light emitting elements a of the same wavelength between each set is 150 μm (30 μm×5=150 μm). Note that this setting is based on the assumption that a system requires an inter-element pitch of 150 μm or more in order to obtain the speckle reduction effect by multiplexing light sources.

By setting the inter-element pitch in such a layout, each light-emitting element a of the same wavelength included in all sets satisfies the inter-element pitch required for multiple light source angle multiplexing, and the adjacent light-emitting elements a in each set Since the light emitting elements a have different oscillation wavelengths, they have different speckle patterns. Therefore, even in the layout of Example 2, the effect of reducing speckle noise depending on the number of light emitting elements can be expected.

When 50 light-emitting elements a are arranged linearly and one-dimensionally as in this example, each light-emitting element a has a single wavelength light source multiplexing, the width is 7.35 mm (calculation formula: 150 μm x (50-1) = 7.35 mm) is now 1.47 mm (calculation formula: 30 μm x (50-1) = 1.47 mm), so even if the chip size is reduced to 1/5, the same 1/ A speckle contrast reduction effect of √50 can be obtained.

Note that the layout shown in FIG. 8 is an example, and the number of light emitting elements included in the light emitting element group, the order of wavelengths, the shape of the opening, the arrangement of the light emitting element group, etc. are not limited to this. In addition to conditions 1 and 2, the number of light emitting elements included in the light emitting element group, the order of wavelengths, the shape of the opening, the arrangement of the light emitting element group, etc. may be modified as appropriate, as long as the conditions for wavelength multiplexing are satisfied.

FIG. 9 shows the order in which light emitting elements of different wavelengths (wavelength λ1, wavelength λ2, wavelength λ3, wavelength λ4, wavelength λ5) in the set are arranged. This is an example of randomization so that they are not in adjacent positions. With this arrangement, the wavelength difference between adjacent light emitting elements is large as shown in Figure 8, which is arranged in order of wavelength, so even if the wavelength finish of each light emitting element varies, the wavelength difference between adjacent light emitting elements can be ensured. Therefore, it is easy to obtain the effect of reducing speckle noise.

Furthermore, as the wavelength difference between elements increases, the pitch between elements necessary to obtain different speckle patterns also decreases, so further miniaturization can be expected depending on the system. In addition, even if the pitch between elements is maintained, the same speckle reduction effect can be obtained even if the overall wavelength difference Δλ (λ1 - λ5) is narrowed, so it is possible to form a structure in which the light emitting elements emit light of different wavelengths. becomes easier.

In Example 2 as well, by integrating light emitting elements with different oscillation wavelengths within the plane of the VCSEL light source, it is possible to reduce speckle noise without increasing the size or cost of the light projecting section. is obtained. Furthermore, since lasers with different wavelengths are used, it is not necessarily necessary to satisfy Condition 2 for a single wavelength, and layout constraints are relaxed. Therefore, since the light emitting elements can be provided at narrower intervals than when multiple light sources are angularly multiplexed, the integration density can be improved. Further benefits can be expected from improved integration density, such as smaller chips and increased design freedom by making use of extra space.

(Example 3)
FIG. 10 is a diagram showing a modified example of the configuration of the VCSEL array 11. The VCSEL array 11 shown in FIG. 10 has at least one light emitting element group a1 called a layer, which is controlled so that a plurality of light emitting elements emit light at the same time. Although FIG. 10 shows the light emitting element group a1 arranged one-dimensionally, it may be arranged two-dimensionally. The light emission timing of each layer 222 is controlled independently.

In the layer 222 shown in FIG. 10, five light emitting elements a2 are arranged in a cross shape. Each light emitting element a2 within the same layer 222 is controlled to emit light at the same timing.

The pitch A of each layer 222 and the pitch (pitch B and pitch C) of each light emitting element a2 shown in FIG. 10 are set based on conditions 1 and 2 of the inter-element pitch of Example 1. Furthermore, in the case where the oscillation wavelength of each light emitting element is made different, the light source of Example 2 is applied.

Note that although five light emitting elements a2 of the layer 222 are shown arranged in a cross shape here, the present invention is not limited to this. The number of light emitting elements a2 may be increased or decreased, or more light emitting elements a2 may be arranged in a layout like a honeycomb structure.

Moreover, although the opening of the light emitting element a2 is shown to be square, it may be of other shapes such as a hexagon.

(Second embodiment)
A projection device including a surface-emitting semiconductor laser according to a first embodiment will be described.
FIG. 11 is a diagram showing an example of the configuration of a projection device according to the second embodiment. The projection device 10 shown in FIG. 11 includes a VCSEL array 11, an optical system 12, and a light deflection element 13.

The optical system 12 is composed of lenses, and guides light emitted from each light emitting element of the VCSEL array 11 to a light deflection element 13.

The light deflection element 13 projects the projection light 14 onto the target 15 by projecting the light from the optical system 12 onto a projection area.

Projection light 14 shown in FIG. 11 is light in which the respective output lights of the light emitting elements a of the VCSEL array 11 overlap, is deflected by the mirror surface of the light deflection element 13, and is projected onto the target 15. In the second embodiment as well, the effect of reducing speckle noise can be obtained by projecting the projection light 14 onto an assumed projection area.

(light deflection element)
The optical deflection element 13 is a movable mirror that can scan laser light in one or two axial directions. Examples of movable mirrors include MEMS (Micro Electro Mechanical Systems) mirrors, polygon mirrors, and galvano mirrors, but other types can be used as long as they can scan laser light in one or two axes. It may also be possible to use In this embodiment, a movable mirror is used that uniaxially scans the line light 14 formed by the optical system 12 onto the measurement target 15 in the scanning range. Note that a two-dimensional projection pattern is formed on the movable mirror by optically scanning the line light.

FIG. 12 is a diagram showing an example of the configuration of a MEMS mirror (also referred to as a MEMS mirror scanner), which is an example of the optical deflection element 13. The MEMS mirror scanner shown in FIG. 12 has a movable part 132 and two sets of meandering beam parts 133 on a support substrate 131.

The movable part 132 includes a reflecting mirror 1320. One end of each of the two sets of meandering beam portions 133 is connected to the movable portion 132, and the other end is supported by the support substrate 131. The two sets of meandering beam sections 133 each consist of a plurality of meander-shaped beam sections, and both include a first piezoelectric member 1331 that deforms when a first voltage is applied, and a second piezoelectric member 1331 that deforms when a second voltage is applied. A piezoelectric member 1332 is provided at every other beam portion. The first piezoelectric member 1331 and the second piezoelectric member 1332 are provided independently for each adjacent beam portion. The two sets of meandering beam portions 133 are deformed by applying a voltage to the first piezoelectric member 1331 and the second piezoelectric member 1332, respectively, and rotate the reflective mirror 1320 of the movable portion 132 around the rotation axis.

Specifically, voltages having opposite phases are applied to the first piezoelectric member 1331 and the second piezoelectric member 1332 to cause each beam portion to warp. As a result, adjacent beam sections are deflected in different directions, which are accumulated, and the reflecting mirror 1320 rotates back and forth about the rotation axis together with the movable section 132 connected to the two sets of meandering beam sections 133. Furthermore, by applying a sine wave with a drive frequency matched to the mirror resonance mode with the rotation axis as the center of rotation to the first piezoelectric member 1331 and the second piezoelectric member 1332 in opposite phases, a very low voltage can be achieved. A large rotation angle can be obtained.

Note that the drive waveform is not limited to a sine wave. For example, it may be a sawtooth wave. Further, the drive is not limited to the resonant mode, but may be driven in a non-resonant mode.

Note that the optical deflection element 13 is not limited to a MEMS mirror, and may be any movable object having a reflecting part that scans light, such as a polygon mirror or a galvano mirror. MEMS mirrors are advantageous in terms of being smaller and lighter. The driving method of the MEMS mirror may be any one of electrostatic, piezoelectric, and electromagnetic methods.

(Third embodiment)
An example in which the surface-emitting semiconductor laser according to the first embodiment is applied to a measuring device will be shown. Here, as an example of a measuring device, an example of application to a three-dimensional measuring device that measures a measurement target will be shown.

FIG. 13 is a diagram showing an example of a measuring device according to the third embodiment. The measurement device 1 shown in FIG. 13 includes a measurement information acquisition unit 20 and a control unit 30.

The measurement information acquisition unit 20 includes a projection device 10 that is a projection means, and a camera 21 that is an imaging means. The projection device 10 includes a VCSEL array 11, an optical system 12, and a light deflection element 13. The measurement information acquisition unit 20 deflects the light from the plurality of light emitting elements a of the VCSEL array 11 using the optical deflection element 13 and projects it onto the measurement area under the control of the control section 31 of the control unit 30. The control unit 31 projects a predetermined pattern of projection light 14 onto the entire measurement area by adjusting the brightness and lighting timing of each light emitting element a of the VCSEL array 11. For example, by controlling the lighting and extinguishing (on/off) of the light emitting element a, projection light 14 having a desired projection pattern such as a black and white gray code pattern is projected.

The position and angle of the camera 21 are fixed such that the projection center 300 of the projection light 14 projected onto the measurement target by the projection device 10 is the center of the imaging region 40 . Thereby, the camera 21 images the projection area.

The camera 21 includes a lens 210 and an image sensor 211. As the image sensor 211, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) image sensor is used. Light incident on the camera 21 forms an image on the image sensor 211 via the lens 210 and is photoelectrically converted. The electrical signal photoelectrically converted by the image sensor 211 is converted into an image signal, and the image signal is output from the camera 21 to the arithmetic processing section 32 of the control unit 30.

The control unit 30 controls the projection of pattern light by the projection device 10, controls the imaging by the camera 21, and performs arithmetic processing such as three-dimensional measurement of the measurement target based on the image signal captured by the camera 21. The control unit 31 may perform control to switch the pattern light projected by the projection device 10 to another pattern light. Further, the control unit 31 may control the arithmetic processing unit 32 to output calibration information used for calculating three-dimensional coordinates.

The control unit 30 has an arithmetic processing section 32 as a measuring means. The arithmetic processing unit 32 calculates (measures) three-dimensional coordinates based on the input image signal and obtains a three-dimensional shape. Further, the arithmetic processing unit 32 outputs three-dimensional shape information indicating the calculated three-dimensional shape to a PC or the like (not shown) according to instructions from the control unit 31. Although FIG. 13 shows a configuration in which one set of measurement information acquisition units 20 is attached to the control unit 30, a plurality of sets of measurement information acquisition units 20 may be attached to the control unit 30.

(Explanation of functional blocks of control unit)
FIG. 14 is a diagram showing an example of a block configuration of the measuring device 1. As shown in FIG. In addition, in FIG. 14, the same reference numerals are given to parts that have already been explained, and detailed explanations are omitted as appropriate.

The arithmetic processing unit 32 shown in FIG. 14 analyzes the image signal output from the camera 21. The arithmetic processing unit 32 performs a three-dimensional information restoration process through arithmetic processing using the analysis result of the image signal and the calibration information, thereby performing three-dimensional measurement of the object. The arithmetic processing unit 32 supplies the restored three-dimensional information to the control unit 31.

The control unit 31 includes a system control unit 310, a pattern storage unit 311, a light source drive/detection unit 312, an optical scanning drive/detection unit 313, and an imaging control unit 314.

The optical scanning drive/detection section 313 drives the optical deflection element 13 under the control of the system control section 310. The system control unit 310 controls the optical scanning drive/detection unit 313 so that the light irradiated onto the deflection center of the optical deflection element 13 irradiates the measurement target. The imaging control unit 314 controls the imaging timing and exposure amount of the camera 21 under the control of the system control unit 310.

The light source drive/detection unit 312 controls lighting and extinguishing of each light emitting element of the VCSEL array 11 under the control of the system control unit 310.

The pattern storage unit 311 reads, for example, pattern information of a projected image stored in a nonvolatile storage medium of the measuring device 1. The pattern information is pattern information for forming a projection image (projection pattern). The pattern storage section 311 reads pattern information according to instructions from the system control section 310 and passes it to the system control section 310. The system control unit 310 controls the light source drive/detection unit 312 based on the pattern information passed from the pattern storage unit 311.

The system control unit 310 instructs the pattern storage unit 311 to read pattern information based on the restored three-dimensional information supplied from the arithmetic processing unit 32. The system control section 310 controls the light source drive/detection section 312 according to the pattern information read out by the pattern storage section 311.

Furthermore, the system control unit 310 instructs the calculation processing unit 32 on a calculation method according to the read pattern information.

The arithmetic processing section 32, system control section 310, and imaging control section 314 are realized by a measurement program running on a CPU (Central Processing Unit). Specifically, the CPU implements the arithmetic processing section 32, the system control section 310, and the imaging control section 314 by reading out and executing a measurement program from a ROM (Read Only Memory). Note that this implementation method is just an example, and is not limited to this. For example, part or all of the arithmetic processing unit 32, system control unit 310, and imaging control unit 314 may be configured by hardware circuits that operate in cooperation with each other. Further, other blocks other than the arithmetic processing section 32, system control section 310, and imaging control section 314 may also be realized by a measurement program.

In the third embodiment, each setting of the measuring device is set as "setting that has the effect of reducing speckle noise." Therefore, spec noise is reduced in the image of the measurement target, and measurement accuracy is improved when analyzing the luminance information of the captured image.

(Fourth embodiment)
Next, a fourth embodiment will be described. The fourth embodiment is an example in which the measuring device 1 according to the third embodiment is used in combination with a robot arm (multi-joint arm).

FIG. 15 is a diagram showing an example of the configuration of a robot according to the fourth embodiment. FIG. 15 shows an example in which the measuring device 1 is applied to a robot arm having multiple joints. The robot arm 70 includes a hand section 71 for picking a target object, and the measuring device 1 is mounted in the immediate vicinity of the hand section 71. The robot arm 70 includes a plurality of bendable movable parts, and changes the position and orientation of the hand part 71 according to control.

The measuring device 1 is provided so that the direction in which the light is projected matches the direction in which the hand section 71 faces, and measures the picking object 15 of the hand section 71 as a measurement object.

As described above, in the fourth embodiment, by mounting the measuring device 1 on the robot arm 70, it is possible to measure the object to be picked from a short distance, which is compared to measuring from a distance using a camera or the like. Improved measurement accuracy can be achieved. For example, in the field of FA (Factory Automation) on various assembly lines in factories, robots such as the robot arm 70 are used to inspect and recognize parts. By mounting the measuring device 1 on a robot, it becomes possible to inspect and recognize parts with high precision.

(Fifth embodiment)
Next, a fifth embodiment will be described. The fifth embodiment is an example in which the measuring device 1 according to the third embodiment is mounted on an electronic device such as a smartphone or a PC.

FIG. 16 is a diagram illustrating an example of the configuration of an electronic device such as a smartphone according to the fourth embodiment. An example in which the measuring device 1 is applied to a smartphone 80 is shown. The smartphone 80 is equipped with the measuring device 1 and a user authentication function. The user authentication function is provided by, for example, dedicated hardware. Note that the "authentication function section" is not limited to dedicated hardware, and may be provided such that the CPU of the computer executes a program such as a ROM to realize this function. The measuring device 1 measures the shape of the user's 81 face, ears, head, and the like. Based on this measurement result, the user authentication function determines whether the user 81 is registered with the smartphone 80.

In this way, in the fifth embodiment, by installing the measuring device 1 in the smartphone 80, it is possible to measure the shape of the face, ears, head, etc. of the user 81 with high accuracy, and the recognition accuracy can be improved. Improvements can be achieved. Note that in this embodiment, the measuring device 1 is installed in the smartphone 80, but it may be installed in an electronic device such as a PC or a printer. Further, in terms of functionality, the present invention is not limited to the personal authentication function, but may also be used as a facial shape scanner.

(Sixth embodiment)
Next, a sixth embodiment will be described. The sixth embodiment is an example in which the measuring device 1 according to the third embodiment is mounted on a moving object.

FIG. 17 is a diagram showing an example of the configuration of a vehicle according to the sixth embodiment. An example in which the measuring device 1 is applied to a car is shown. A measuring device 1 and a driving support function are installed in the automobile interior 85. The driving support function is provided by, for example, dedicated hardware. Note that the "driving support section" is not limited to dedicated hardware, and may also be configured such that a CPU of a computer executes a program such as a ROM to realize this function. The measuring device 1 measures the face, posture, etc. of the driver 86. Based on this measurement result, the driving support function provides appropriate support according to the driver's 86 situation.

As described above, in the sixth embodiment, by mounting the measuring device 1 on a car, it is possible to measure the face, posture, etc. of the driver 86 with high precision, and the accuracy of recognizing the condition of the driver 86 inside the car 85 can be improved. Improvements can be achieved. In this embodiment, the measuring device 1 is installed in a car, but it may also be installed in the inside of a train, the cockpit (or passenger seat), etc. of an airplane. Further, in terms of functionality, the present invention is not limited to recognizing the driver's 86's condition such as his face and posture, but may also be used to recognize passengers other than the driver 86 or the state of the interior of the vehicle 85. It may also be used for vehicle security, such as performing personal authentication of the driver 86 and determining whether the person is registered in advance as a driver of the vehicle.

FIG. 18 is a diagram illustrating an example of the configuration of another moving body according to the sixth embodiment. FIG. 18 shows an example in which the measuring device 1 is applied to an autonomous moving body. The measuring device 1 is mounted on the moving body 87 and measures the surroundings of the moving body 87. Based on this measurement result, the moving object 87 determines its own moving route and calculates the layout of the room 89, such as the position of the desk 88.

In this manner, in the sixth embodiment, by mounting the measuring device 1 on the moving body 87, the surroundings of the moving body 87 can be measured with high precision, and driving of the moving body 87 can be supported. Note that in this embodiment, the measuring device 1 is mounted on a small moving body 87, but it may be mounted on an automobile or the like. Further, it may be used not only indoors but also outdoors, and may be used for measuring buildings and the like.

(Seventh embodiment)
Next, a seventh embodiment will be described. The seventh embodiment is an example in which the measuring device 1 according to the third embodiment is mounted on a modeling device.

FIG. 19 is a diagram showing an example of the configuration of a modeling apparatus according to the seventh embodiment. FIG. 19 shows an example in which the measuring device 1 is applied to a head section 91 of a 3D printer 90, which is an example of a modeling device. The head section 91 is an example of a "head" and has a nozzle 93 that discharges a modeling liquid for forming the object 92. The measuring device 1 measures the shape of the formed object 92 formed by the 3D printer 90 during formation. Based on this measurement result, formation control of the 3D printer 90 is performed.

In this manner, in the seventh embodiment, by mounting the measuring device 1 on the 3D printer 90, the shape of the formed object 92 can be measured during formation, and the formed object 92 can be formed with high precision. Note that in this embodiment, the measuring device 1 is mounted on the head section 91 of the 3D printer 90, but it may be mounted at another position within the 3D printer 90.

11 VCSEL array a Light emitting element D Pitch (element spacing)
LWD distance θ angle

Japanese Patent Application Publication No. 2009-146941

Claims (12)

It has a plurality of light emitting elements each emitting light of a predetermined oscillation wavelength in a plane,
The element arrangement of the plurality of light emitting elements is
In the assumed projection area, the irradiated light of the plurality of light emitting elements satisfies an overlapping element interval, and the speckle pattern of each of the irradiated lights obtained in the assumed projection area satisfies a different element interval for each irradiated light,
A light emitting element group including at least one light emitting element each having a different oscillation wavelength is the minimum unit of the plurality of light emitting elements, and a plurality of light emitting element groups of the plurality of minimum units are arranged such that the light emitting elements having the same oscillation wavelength are periodic. arranged to take a position,
The light emitting elements included in the minimum unit light emitting element group are:
The wavelength difference between the oscillation wavelength of the light emitted by the light emitting elements adjacent to one side is the wavelength difference when the oscillation wavelengths of the light emitted by the light emitting elements of the minimum unit light emitting element group are arranged in order of wavelength. greater than
A light source characterized by: The element arrangement of the plurality of light emitting elements is
As the number of light emitting elements increases, the speckle contrast obtained in the assumed projection area satisfies an element spacing that follows a theoretical value curve of speckle contrast obtained when different speckle patterns overlap. The light source according to claim 1, characterized in that: The light source according to claim 1, wherein an element spacing between light emitting elements having different oscillation wavelengths within the plane is narrower than an element spacing between light emitting elements having the same oscillation wavelength. 4. The light source according to claim 3, wherein the light emitting elements of each oscillation wavelength are arranged at the same element interval. The light source according to any one of claims 1 to 4 , wherein the light emitting elements included in the minimum unit light emitting element group are arranged two-dimensionally. The light source according to any one of claims 1 to 5 ,
an optical system that guides light from each of the light emitting elements of the light source;
a light deflection element that reflects the light guided by the optical system to the projection area;
A projection device comprising: The projection device according to claim 6 ;
imaging means for imaging the projection area;
Measuring means for measuring a measurement target in the projection area based on information captured by the imaging means;
A measuring device comprising: A measuring device according to claim 7 ,
a multi-jointed arm equipped with the measuring device;
A robot characterized by being equipped with. A measuring device according to claim 7 ,
an authentication unit that authenticates a user based on a measurement result of the user by the measuring device;
An electronic device characterized by comprising: A measuring device according to claim 7 ,
a driving support unit that supports driving of the mobile object based on measurement results by the measuring device;
A mobile object comprising: A measuring device according to claim 7 ,
a head that forms a formed object based on measurement results by the measurement device;
A modeling device characterized by comprising: A light source having a plurality of surface emitting elements each emitting light of a predetermined oscillation wavelength,
The element arrangement of the plurality of surface emitting elements is such that among the plurality of surface emitting elements, the irradiation light of at least adjacent surface emitting elements overlaps, and the speckle pattern in the irradiation area of the irradiation light is The element spacing is set to be different for each of the irradiated lights ,
A light-emitting element group including at least one surface-emitting element having a different oscillation wavelength is the minimum unit of the plurality of surface-emitting elements, and a plurality of light-emitting element groups of the plurality of minimum units are the surface-emitting elements having the same oscillation wavelength. are arranged so that they take periodic positions,
The surface emitting element included in the minimum unit light emitting element group is
When the oscillation wavelengths of light emitted by the surface emitting elements of the minimum unit light emitting element group are arranged in order of wavelength, the difference in wavelength between the oscillation wavelength of light emitted by the surface emitting element adjacent to one side is greater than the wavelength difference
A light source characterized by:

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